Hi Wizard, nice to hear back from you and I may repeat what I have already said, sorry.
Intrusive thoughts may not seem to be visible, normally the person suffers in silence and maybe afraid of telling anyone but can happen after a certain amount of time because it begins to worry them, that's what happened with me, I eventually told my ex-wife, who said 'don't be silly' and that's why I kept it to myself, only my psychologist knew, previoiusly my older brother chastised me.
I have learned to hide all my OCD habits, checking the lock, light switch, the knobs on the stove as I've mentioned above.
If a person who can’t get over OCD may feel as though it's because they are weak or defective so it makes people hide their illness from friends and family.
I don't take myself as being weak or defective, I am have an illness that can be treatable for some people.
If someone goes to check the door lock twice on one or two occasions doesn't mean they have OCD, it's when it becomes an obsession.
Everyone with OCD has their own reason why they have to check the door lock and if you move house then the previous obsession/habit may stop but replaced by another one.
I couldn't walk on concrete cracks on the footpath before, now it doesn't worry me, and all of a sudden a thought may come to mind so a new habit/ritual starts but that could be temporary.
If you tell someone not to check the door lock then the anxiety builds up for.